题解 | #统计每个学校的答过题的用户的平均答题数#
统计每个学校的答过题的用户的平均答题数
https://www.nowcoder.com/practice/88aa923a9a674253b861a8fa56bac8e5
select u.university,count(q.question_id) / count(distinct(u.device_id)) as avg_answer_cnt from user_profile u, question_practice_detail q where u.device_id = q.device_id group by u.university
